Process for the production of alkali-metal silicates that are soluble in water



Patented June 25, 1929. p

UNITED STATES PATENT OFFICE.

BIRGER FJELD HALVORSEN, OF OSLO. NORWAY. ASSIGNOR TO NORSK HYDRO- ELEILTRISK KVAELSTOFAKTIESELSKAB, OF OSLO, NORWAY.

PROCESS FOR THE PRODUCTION OF ALKAIdI-METAL SILICATES THAT ARE SOLUBLEIN WATER.

No Drawing. Application filed May 14, 1925, Serial No. 30,366, and inNorway May 19, 1924.

As it is known, alkali metal silicates that ous earth reacts in the sameway as artificial, are soluble 'in water (soluble glass) areprohydrated, silicic acid. duced by melting pure sand with alkali metalBy employing the above method with a carbonates or sulphates and coal inglass fursilicic acid residue obtained by treating solunaces. Thesesilicates have also been proble silicates with an acid, or by using itwith duced on a smaller scale by treating diatomadiatomaceous earth,there is the advantage coous earth with alkali metal hydroxide. It thatthe process can be performed at a comhas also been suggested that alkalimetal siliparatively low temperature. The loss of nicates be produced bymelting. the alkali metal trogen which, ifthe mass has to be melted, isnitrates with quartz sand. This method has rather large, is therebyreduced. The use of not, however, lead to any result thatcan be ofmelting furnaces is avoided as well as the distechnical use andconsequently it has never advantages pertaining thereto and the processbeen employed on an industrial scale. can be effected in closedfurnacesystems, so According to the present invention, howthat the masscan-either be heated directly by ever, soluble glass can be producedfrom hymeans of hot gases, for instance, from an elecdrated silicic acidand compounds of alkali tric nitrogen oxidation furnace, or it can bemetal, oxygen and nitrogen, when adopting heated indirectly, by means ofordinary heatthe following method. ing gases. By using the residue fromsoluble If, as a raw material, silicates in their natusilicates, anunpleasant waste product is utilral state that are decomposed by acidare used, ized which would otherwise accumulate in for instance,labradorite, leucite or similar large quantities round those factorieswhich material, these silicates are treated first in the manufacturealumina and alkali metal comusual manner with an acid, for instance,pounds from such silicates. nitric acid, which dissolves the bases andIf nitrate of potassium or a substance which leaves behind the silicicacid in a hydrated, contains considerable quantities of nitrate ofporous and very pure state. This silicic potassium is chosen as thealkali metal-oxyacid is then mixed with an alkalimetal-nitrogen-nitrogen compound, a porous, easily pulgen-oxygencompound, for instance, Chilean verized' product is obtained which makesan nitrate, a nitrite or a mixture of nitrite and excellent fertilizer,as besides containing ponitrate, such as is obtained, for example,tassium, it also contains silicic acid in an when nitrous gases areabsorbed in alkaline easily soluble state, which according toProsolutions. The mixture is heated to such a fessor Lemmermann, canpartly replace phosdegree that alkali metal silicates are formed phoricacid. whilst the nitrogenoxides are expelled. This Thus it is possibleto utilize, in a very reaction commences at 250 G., and theconprofitable way, certain kinds of rock, such as version process isconcluded at 600-700 O. leucite, that contain potassium and aresoluwithout the mass melting. The reaction ble in acid. If the rock isdissolved in nitric product is extremely porous and is easily disacid,nitrate of potassium is obtained. This solved in water, especially if asomewhat is then mixed with a part of the silicic acid highertemperature and pressure is used. and is heated, whereby silicate ofpotassium After filtering, a solution of pure soluble that is soluble inwater is obtained. The solglass is obtained. The nitrous gases whichvent used, nitric acid, is recovered and can be escape are converted bythe well-known methused again. so that by'means of a comparaod intonitric acid. Thus the alkali that-is tively small amount of acid largequantities necessary for the formation of alkali metal of fertilizer canbe produced.

silicates is cheaply obtained, as it is the nitro? By heating variousamounts of the residue gen content only that decides the price of the'of leucite (from 3 to 5 molecules of SiO )"with alkali metal compound,and the nitrogen used the same quantity of sodium nitrite (1 molein theprocess is recovered in the formof cule of Na O) to 630 C. and treatingthe nitric acid, silicic acid in its natural state, product thusobtained with water, solutions diatomaceous earth, can also be used inthis can be produced that contain from 1.85 to 2.8 process as it hasbeen proved that diatomacemol. of S iO per mol. ofNa o.

The following may be stated as examples of how the method may beperformed:

(1) 8 portions of sodium nitrite and 20 portiois of diatomaceous earthare heated to 600 t (2) 10 portions of sodium nitrite and 2'5 portionsof leucite residue are heated to 610 C.

(3) 6 portions of sodium nitrate and 12.5 portirgis of residue ofleucite are heated to 610 (4) 1O portions of potassium nitrate and.

11 portions of residue of leucite are heated to 600 C.

Claims:

1. Process for the production of alkali metal silicates soluble inwater, consisting in mixing compounds of an alkali metal with nitrogenand oxygen with silicic acid hydrate and heating to 250 C. or more, butbelow the melting point of the mass.

2. Process for the production of alkali mettrate with a part of saidresidue, and heating;

the mixture to a temperature of 250 C. or more but below the meltingpoint of the mass.

4; Process for the production of alkali metal silicates soluble inwater, consisting in mixing compounds of an alkali metal with nitrogenand oxygen with silicic acid hydrate and heating to about 600 C. e

In testimony whereof, I afiix my signature. BIRGER FJELD .HALVORSEN.

